Digital Battery Meter
Voltage of a fully charged 12V battery is no lower than 12.6 volts. A 40% charge will read 12.2V.
Do not draw a 12V battery below a 40% charge (12.2V). Drawing below this point will reduce the battery's ability to hold a charge and/or be recharged back to full (over 12.6V). Batteries MUST remain fully charged in freezing conditions.